In vivo resistance of a laboratory-selected Aspergillus fumigatus isolate to amphotericin B.
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ABSTRACT:
SUBMITTER: Manavathu EK
PROVIDER: S-EPMC538856 | biostudies-other | 2005 Jan
REPOSITORIES: biostudies-other
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Project description:Amphotericin B (AMB) is the most widely used polyene antifungal drug for the treatment of systemic fungal infections including invasive aspergillosis. We aimed to understand molecular targets of AMB in Aspergillus fumigatus (Afu) by genomic approaches. Keywords: Aspergillus fumigatus treated with amphotericin B for 24 hours
2008-02-14 | GSE10505 | GEO
Project description:Amphotericin B (AMB) is the most widely used polyene antifungal drug for the treatment of systemic fungal infections including invasive aspergillosis. We aimed to understand molecular targets of AMB in Aspergillus fumigatus (Afu) by genomic approaches. Amphotericin B (AMB) is the most widely used polyene antifungal drug for the treatment of systemic fungal infections including invasive aspergillosis. We aimed to understand molecular targets of AMB in Aspergillus fumigatus (Afu) by microarray and proteomic methods. Keywords: Aspergillus fumigatus treated with amphotericin B for 24 hours Experiment was performed in dye swap manner from two different biological replicates
2010-05-26 | E-GEOD-10505 | biostudies-arrayexpress
Project description:Amphotericin B (AMB) is a major fungicidal polyene agent that has a broad spectrum of action against invasive fungal infections. AMB is typically used as the last-line drug against serious and life-threatening infections when other drugs have failed to eliminate the fungal pathogens. Recently, AMB resistance in Aspergillus fumigatus has become more evident. For example, a high rate of AMB resistance (96%) was noted in the A. fumigatus population in Hamilton, Ontario, Canada. AMB-resistant strains have also been found in other countries. However, the mechanism of AMB resistance remains largely unknown. Here, we investigated the potential genes and mutations associated with AMB resistance using whole-genome sequences and examined AMB resistance distribution among genetic populations. A total of 196 whole-genome sequences representing strains from 11 countries were examined. Analyses of single nucleotide polymorphisms (SNPs) at the whole-genome level revealed that these strains belonged to three divergent genetic clusters, with the majority (90%) of AMB resistant strains located in one of the three clusters, Cluster 2. Our analyses identified over 60 SNPs significantly associated with AMB resistance. Together, these SNPs represent promising candidates from which to investigate the putative molecular mechanisms of AMB resistance and for their potential use in developing rapid diagnostic markers for clinical screening of AMB resistance in A. fumigatus.
| S-EPMC7713013 | biostudies-literature
Project description:Amphotericin B (AMB) is the most widely used polyene antifungal drug for the treatment of systemic fungal infections, including invasive aspergillosis. It has been our aim to understand the molecular targets of AMB in Aspergillus fumigatus by genomic and proteomic approaches. In transcriptomic analysis, a total of 295 genes were found to be differentially expressed (165 upregulated and 130 downregulated), including many involving the ergosterol pathway, cell stress proteins, cell wall proteins, transport proteins, and hypothetical proteins. Proteomic profiles of A. fumigatus alone or A. fumigatus treated with AMB showed differential expression levels for 85 proteins (76 upregulated and 9 downregulated). Forty-eight of them were identified with high confidence and belonged to the above-mentioned categories. Differential expression levels for Rho-GDP dissociation inhibitor (Rho-GDI), secretory-pathway GDI, clathrin, Sec 31 (a subunit of the exocyst complex), and RAB GTPase Ypt51 in response to an antifungal drug are reported here for the first time and may represent a specific response of A. fumigatus to AMB. The expression of some of these genes was validated by real-time reverse transcription-PCR. The AMB responsive genes/proteins observed to be differentially expressed in A. fumigatus may be further explored for novel drug development.
| S-EPMC2592866 | biostudies-literature
Project description:Transcriptome of A. fumigatus shifted from ammoniumtartrate to different nitrogen sources and incubated for a defined time was compared. After 16h preculture, the fungus was transferred into fresh medium containing ammonium tartrate, sodium nitrate, proline or bsa as nitrogen source. After 1h, fungus was reisolated, RNA was prepared from fungus, transcriptome was assessed and used for further analysis.
2011-10-30 | GSE30384 | GEO
Project description:The origin of isolates routinely used by the community of Aspergillus fumigatus researchers is periodically a matter of intense discussion at our centre, as the construction of recombinant isolates have sometimes followed convoluted routes, the documentation describing their lineages is fragmented, and the nomenclature is confusing. As an aide memoir, not least for our own benefit, we submit the following account and tabulated list of strains (Table 1) in an effort to collate all of the relevant information in a single, easily accessible document. To maximise the accuracy of this record we have consulted widely amongst the community of Medical Mycologists using these strains. All the strains described are currently available from one of these organisations, namely the Fungal Genetics Stock Centre (FGSC), FungiDB, Ensembl Fungi and The National Collection of Pathogenic Fungi (NCPF) at Public Health England. Display items from this manuscript are also featured on FungiDB.Lay abstractWe present a concise overview on the definition, origin and unique genetic makeup of the Aspergillus fumigatus isolates routinely in use by the fungal research community, to aid researchers to describe past and new strains and the experimental differences observed more accurately.
| S-EPMC7779236 | biostudies-literature
Project description:BACKGROUND The aim of this study was to evaluate the dispersal effects of 3,5-dicaffeoylquinic acid (3,5-DCQA) against the preformed biofilm of Aspergillus fumigatus and to investigate its potential mechanism. MATERIAL AND METHODS Aspergillus fumigatus biofilms of laboratory strain AF293 and clinical strain GXMU04 were generated in 24- or 96-well polystyrene microtiter plates in vitro. Crystal violet assay and XTT reduction assay were performed to evaluate the effects of 3,5-DCQA on biofilm biomass, extracellular matrix, and metabolic activity alteration of cells in biofilms. Real-time PCR was performed to quantify the expression of hydrophobin genes. The cytotoxicity of 3,5-DCQA on human erythrocytes was evaluated by a hemolytic assay. RESULTS The results indicated that 3,5-DCQA in subminimum inhibitory concentrations (256 to 1024 mg/L) elicited optimal A. fumigatus biofilm dispersion activity and improved the efficacy of VRC and AMB in minimal fungicidal concentrations (MFCs) to combat fungal cells embedded in biofilms. The results of scanning electron microscope (SEM) and confocal laser scanning microscopy (CLSM) revealed 3,5-DCQA facilitated the entry of antifungal agents into the A. fumigatus biofilm through eliminating the hydrophobic extracellular matrix (ECM) without affecting fungal growth. Real-time PCR indicated that 3,5-DCQA down-regulated the expression of hydrophobin genes. Hemolytic assay confirmed that 3,5-DCQA exhibited a low cytotoxicity against human erythrocytes. CONCLUSIONS Subminimum inhibitory concentrations of 3,5-DCQA can disperse A. fumigatus biofilm and enhance fungicidal efficacy of VRC and AMB through down-regulating expression of the hydrophobin genes. The study indicated the anti-biofilm potential of 3,5-DCQA for the management of A. fumigatus biofilm-associated infection.
| S-EPMC5788051 | biostudies-literature
Project description:Respiratory tract colonization by molds in patients with cystic fibrosis (CF) were analyzed, with particular focus on the frequency, genotype, and underlying mechanism of azole resistance among Aspergillus fumigatus isolates. Clinical and demographic data were also analyzed. A total of 3,336 respiratory samples from 287 CF patients were collected during two 6-month periods in 2007 and 2009. Azole resistance was detected using an itraconazole screening agar (4 mg/liter) and the EUCAST method. cyp51A gene sequencing and microsatellite genotyping were performed for isolates from patients harboring azole-resistant A. fumigatus. Aspergillus spp. were present in 145 patients (51%), of whom 63 (22%) were persistently colonized. Twelve patients (4%) harbored other molds. Persistently colonized patients were older, provided more samples, and more often had a chronic bacterial infection. Six of 133 patients (4.5%) harbored azole-nonsusceptible or -resistant A. fumigatus isolates, and five of those six patients had isolates with Cyp51A alterations (M220K, tandem repeat [TR]/L98H, TR/L98H-S297T-F495I, M220I-V101F, and Y431C). All six patients were previously exposed to azoles. Genotyping revealed (i) microevolution for A. fumigatus isolates received consecutively over the 2-year period, (ii) susceptible and resistant isolates (not involving TR/L98H isolates) with identical or very closely related genotypes (two patients), and (iii) two related susceptible isolates and a third unrelated resistant isolate with a unique genotype and the TR/L98H resistance combination (one patient). Aspergilli were frequently found in Danish CF patients, with 4.5% of the A. fumigatus isolates being azole nonsusceptible or resistant. Genotyping suggested selection of resistance in the patient as well as resistance being achieved in the environment.
| S-EPMC3122734 | biostudies-literature
Project description:Aspergillus fumigatus biofilms represent a problematic clinical entity, especially because of their recalcitrance to antifungal drugs, which poses a number of therapeutic implications for invasive aspergillosis, the most difficult-to-treat Aspergillus-related disease. While the antibiofilm activities of amphotericin B (AMB) deoxycholate and its lipid formulations (e.g., liposomal AMB [LAMB]) are well documented, the effectiveness of these drugs in combination with nonantifungal agents is poorly understood. In the present study, in vitro interactions between polyene antifungals (AMB and LAMB) and alginate lyase (AlgL), an enzyme degrading the polysaccharides produced as extracellular polymeric substances (EPSs) within the biofilm matrix, against A. fumigatus biofilms were evaluated by using the checkerboard microdilution and the time-kill assays. Furthermore, atomic force microscopy (AFM) was used to image and quantify the effects of AlgL-antifungal combinations on biofilm-growing hyphal cells. On the basis of fractional inhibitory concentration index values, synergy was found between both AMB formulations and AlgL, and this finding was also confirmed by the time-kill test. Finally, AFM analysis showed that when A. fumigatus biofilms were treated with AlgL or polyene alone, as well as with their combination, both a reduction of hyphal thicknesses and an increase of adhesive forces were observed compared to the findings for untreated controls, probably owing to the different action by the enzyme or the antifungal compounds. Interestingly, marked physical changes were noticed in A. fumigatus biofilms exposed to the AlgL-antifungal combinations compared with the physical characteristics detected after exposure to the antifungals alone, indicating that AlgL may enhance the antibiofilm activity of both AMB and LAMB, perhaps by disrupting the hypha-embedding EPSs and thus facilitating the drugs to reach biofilm cells. Taken together, our results suggest that a combination of AlgL and a polyene antifungal may prove to be a new therapeutic strategy for invasive aspergillosis, while reinforcing the EPS as a valuable antibiofilm drug target.
| S-EPMC3591909 | biostudies-other
Project description:Aspergillus fumigatus is a filamentous fungus that can cause a life-threatening invasive pulmonary aspergillosis (IPA) in immunocompromised individuals. We previously characterized an exo-sialidase from A. fumigatus that prefers the sialic acid substrate, 2-keto-3-deoxy-D-glycero-D-galacto-nononic acid (Kdn); hence it is a Kdnase. Sialidases are known virulence factors in other pathogens; therefore, the goal of our study was to evaluate the importance of Kdnase in A. fumigatus. A kdnase knockout strain (?kdnase) was unable to grow on medium containing Kdn and displayed reduced growth and abnormal morphology. ?kdnase was more sensitive than wild type to hyperosmotic conditions and the antifungal agent, amphotericin B. In contrast, ?kdnase had increased resistance to nikkomycin, Congo Red and Calcofluor White indicating activation of compensatory cell wall chitin deposition. Increased cell wall thickness and chitin content in ?kdnase were confirmed by electron and immunofluorescence microscopy. In a neutropenic mouse model of invasive aspergillosis, the ?kdnase strain had attenuated virulence and a significantly lower lung fungal burden but only in animals that received liposomal amphotericin B after spore exposure. Macrophage numbers were almost twofold higher in lung sections from mice that received the ?kdnase strain, possibly related to higher survival of macrophages that internalized the ?kdnase conidia. Thus, A. fumigatus Kdnase is important for fungal cell wall integrity and virulence, and because Kdnase is not present in the host, it may represent a potential target for the development of novel antifungal agents.
| S-EPMC5778107 | biostudies-literature